ABSTRACT
Mitogen-activated protein kinase (MAPK) pathway plays a major role in pediatric low-grade gliomas (pLGGs). Immunohistochemistry with mutant-specific antibody, VE1, has appeared to be the most affordable and rapidly deployable method to identify tumors with aberrant MAPK signaling pathway, by highlighting tumor with BRAFV600E mutation. Nonetheless, positive staining cases but not associated with BRAFV600E mutation are also seen. We analyzed 62 pLGGs for the two commonest genetic aberrations in MAPK pathway: KIAA1549-BRAF fusion, using reverse-transcriptase polymerase chain reaction, and BRAFV600E mutation, using VE1 antibody and Sanger sequencing. We recorded a specificity and accuracy rate of 68.75% and 75%, respectively, for VE1, when strong cytoplasmic staining is observed. Interestingly, we observed that cells with ganglionic features frequently bind VE1 but not associated with BRAFV600E mutation. Such observation was also confirmed in four cases of differentiating neuroblastoma. This false positive staining may serve as an important confounder in the interpretation of VE1 immunoreactivity with major therapeutic implication. It is important to confirm the presence of BRAFV600E mutation by DNA-based method, especially in tumor entities not known to, or rarely harbor such mutations.
Subject(s)
Antibodies, Monoclonal , Brain Neoplasms/genetics , Brain Neoplasms/pathology , Glioma/genetics , Glioma/pathology , Staining and Labeling/methods , Gene Fusion , Humans , MAP Kinase Signaling System , Membrane Proteins/genetics , Mutation , Proto-Oncogene Proteins B-raf/geneticsSubject(s)
Ileum/pathology , Lymphangiectasis, Intestinal/pathology , Adolescent , Colonoscopy , Diet, Fat-Restricted , Endoscopy, Digestive System , Humans , Lymphangiectasis, Intestinal/diagnosis , Lymphangiectasis, Intestinal/diet therapy , Male , Triglycerides/administration & dosage , Triglycerides/chemistryABSTRACT
Perivascular epithelioid cell tumour (PEComa) is a term applied to a family of mesenchymal tumours composed of varying proportions of spindle and epithelioid cell components associated with HMB-45 expression. PEComa rarely arises in the soft tissue, visceral organs, skin and bone. This report details an instance when a purely epithelioid PEComa arose from the right fibula of a 52-year-old Chinese woman without features of tuberous sclerosis complex. The excision specimen disclosed an epithelioid tumour with a nested pattern associated with areas of nuclear pleomorphism, mitotic activity, necrosis and vascular invasion in addition to HMB-45 expression on immunohistochemistry. To the best of the authors' knowledge, this represents the first case of a histologically malignant PEComa of the bone. A short review of primary bone PEComas and potential problems in diagnosis is presented.
